Collet



Sept 28, 1965 E. s. FIRESTONE r-:TAL 3,208,759

COLLET Filed Dec. 5, 1965 3 Sheets-Sheet 1 BYCH/S 5/(005 6144/90 SePt- 28, 1965 E. s. FIRESTONE ETAL 3,208,759

COLLET 5 Sheets-Sheet 2 Filed Deo. 5, 1965 Sept. 28, 1965 E. s. FIRESTONE ETAL COLLET 3 Sheets-Sheet 5 Filed Deo. 5, 1965 .Fifa 6.

INVENTORS. UGM/5. F/APSM/V @M7/5 5km/564490 ,47' ADA/5K5 United States Patent O 3,208,759 COLLET Eugene S. Firestone, North Hollywood, and Chris Skousgaard, Lake Arrowhead, Calif.; said Skousgaard assignor to said Firestone, doing business as E. S. Firestone Engineering Co., North Hollywood, Calif.

Filed Dee. 5, 1963, Ser. No. 328,278 4 Claims. (Cl. 279-4) This invention relates to a collet and more particularly to a hydraulically actuated device for operating a split ring type collet in which due to the mechanical advantages inherent in the structure greatly increased torque may be applied to the work without slippage.

It is :a feature of this invention that a pair of pistons are provided and are operable respectively to open and close the collet.

It is another feature of this invention that a plurality of balls is mounted in a race, the individual balls being mounted for movement into and out of said race on actuation of the collet.

These and other objects, features and advantages will be apparent from the annexed specification in which:

FIGURE 1 is a side view partly in section of the device embodying the present invention;

FIGURE 2 is a section taken along the line 2-2 of FIGURE 1;

FIGURE 3 is a plan view taken along the line 3 3 of FIGURE l;

FIGURE 4 is a section taken along the line 4-4 of FIGURE l;

FIGURE 5 is a vertical section through the device in its open position; and

FIGURE 6 is a plan view of the device shown in FIG- URE 5.

Referring now more particularly to the drawings, the invention includes a body 10 generally in the shape of a hanged cylinder to which there is aixed a cap 11 by means of cap screws 12. The cap 11 has a central circular opening 13 therein. Mounted within the generally cylindrical body 10 is an upper piston 14, the upper piston 14 having a depending flange 15 which has a beveled inner wall 16, a beveled end wall 17 and a notch 18. The cap 11 on its lower side is relieved as at 19 to form a cuplike member adapted to receive the horizontal portion of the upper wall of the piston 14 when the device is in the open position as indicated in FIGURE 5. A ball base 20 is provided having a ball supporting upper wall 21 and an outwardly extending flange 22. One wall 23 of the ball base is beveled as indicated to match the bevel 16 of the piston 14. The collet nut 24 is mounted in the bottom of the body 10 and has an outwardly extending flange 25 by which it is secured to the body by means of a snap ring 26 engaging the flange 25 and seating in an annular groove 27 in the body. A spacer 28 is mounted on the ange of the collet nut 24 and has a notch 29 in its upper end to receive an O-ring 30 for sealing the spacer to the body 10. The spacer 28 has an inwardly extending flange 31 which is beveled as at 32. A lower piston 33 is mounted in the body 10 below the ball base 2t) and has a side wall 34 beveled to match the bevel 32 of the spacer. Downwardly extending portion 35 of the piston 33 has an annular groove 36 therein for receiving an O-ring 37 to seal the piston 33 to the spacer 28. A sleeve 40 is provided centrally of body 10 and extending through circular opening 13 in the cap 11. The inner wall 41 of the piston 14 slideably engages the outer wall 42 of the sleeve and the piston 14 has an annular groove 43 therein receiving an O-ring 44 for sealing the piston 14 to the sleeve 40. The piston 14 has an annular groove 45 in its outer wall receiving an O-ring 46 for sealing piston 14 to the inner wall of the body 10.

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An annular groove 48 in the lower end of the sleeve 40 is adapted to receive a snap ring 49 to attach the sleeve 40 to the piston 33 as indicated and the piston 33 has an annular groove 50 to receive an O-ring 51 to seal the piston 33 to the sleeve 40. The sleeve 40 at its upper end is beveled as at 52 and the cap 11 has an annular groove 53 therein for receiving an O-ring 54 to seal the sleeve 40 to the cap 11. The sleeve 40 is provided with a ange 56 which has a horizontal upper wall 57 and a tapered lower wall 59 and a tapered outer wall 58. The taper of the outer wall 58 matches the taper 16 of the taper piston 14. A plurality of balls 60 are seated on the ball base 20. In practice sixteen balls of .375 inch diameter are employed. A keyway 62 is formed in the sleeve 40 and a matching keyway 63 is formed in the ball base 20 so that the sleeve 40 may be keyed and prevented from rotating by a key 64 mounted in the keyways. An air tting 66 supplies air to the space above piston 14 and an air fitting 67 supplies air to the space below the piston 14 and by means of one or more passages 68 in the ball base 20 air is supplied to the top of piston 33.

Referring now more particularly to FIGURES 1 and 5, the device is illustrated as in use with a split ring type collet 70, which collet is split throughout only a portion of its length and is solid in the region 71 where it is threaded to mate with the threads of the collet nut 24. The collet is generally cylindrical in shape, but adjacent its upper end is beveled outwardly as at 72 on a taper complementary to the bevel 52 on the upper end of the sleeve 40. In FIGURES 1 and 5 the device is shown as containing a work piece 75.

The operation of the above-described device is as follows. With the collet being in the open position as shown in FIGURES 5 and 6, the work piece 75 is inserted. Air is then passed under pressure through the air fitting 66 into the space above the piston 14. This drives the piston 14 from the position shown in FIGURE 5 to the position shown in FIGURES l and 2. In so doing the bevel 16 on piston 14 engages the balls 60 and forces them back into fully seated position as shown in FIGURES l and 2. As the balls 60 are forced inwardly they engage the taper 59 on the flange 56 of sleeve 40 which forces the sleeve upwardly. As the sleeve 40 passes upwardly the taper 52 presses against the taper 72 of the collet and forces the collet into closed or gripping position as shown in FIGURES 3 and 4.

When it is desired to open the collet air is passed through air inlet 67 into the space below the piston 14 and through passages 68 into the space above the piston 33. This forces the piston 33 downward and the piston 14 upward. As the piston 14 moves upwardly it frees the balls 60 and permits them to move outwardly as the downward motion of the piston 33 brings the sleeve 40 downward into the open position.

The device is designed for use with any type of working tool and is conventionally provided with a series of cap screw holes 81 in the flange of the body 10 by which the device can be attached to the bed of a lathe, drill press or other machine.

In a device constructed in accordance with the aboveidentified invention, the piston 14 was designed to move approximately 3/8 of an inch which caused the sleeve 40 to move approximately 3%000 of an inch which gives a mechanical advantage of 12 to l. The working area of the piston 14 is approximately ve square inches and the air line pressure generally used is one hundred pounds per square inch. Thus, there is a ve hundred pound force on the piston and at the 12 to 1 mechanical advantage there is a six thousand pound force on the sleeve. The result of the foregoing is that this collet is able'to withstand very .high torque and solidly and iirmly grip the workpiece under substantially any operational conditions.

While we have shown piston 14 in one piece it can alternately be made of two pieces and the beveled surface 16 may be the conventional surface of the Timken roller bearing.

While there has been described what is at present considered the preferred embodiment of the present invention, it will be appreciated by those skilled in the art that various changes and modifications can be made therein without departing from the essence of the invention and it is intended herein to cover all such changes and modifications as come within the true spirit and scope of the appended claims.

We claim:

1. A collet comprising: a generally cylindrical body member; a first piston in said body member; means for applying air under pressure to the top of said first piston; a second piston mounted in said body member; means for supplying air to the bottom of said first piston and to the top of said second piston; a sleeve mounted in said body member and operably connected to said second piston for movement therewith, said sleeve vhaving a frusto-conical upper section adapted toengage the tapered wall of a split ring collet to close said collet; means associated with said first piston to raise said sleeve on operation of said first piston; and means associated with said second piston adapted to lower said sleeve on operation of said second piston.v

2. A collet comprising: a generally cylindrical body member; a first piston in said body member; means for applying air under pressure to the top of said first piston; a second piston mounted in said body member; means for supplying air to the bottom of said first piston and to the top of said second piston; a sleeve mounted in said body member and operably connected to said second piston for movement therewith, said sleeve having a frusto-conical upper section adapted to engage the tapered wall of a split ring collet to close said collet; means associated with said first piston to raise said sleeve on opera tion of said first piston; means associated with said second piston adapted to lower said sleeve on operation of said second piston; the total movement of said first piston being substantially twelve times that of said sleeve.

3. A collet comprising: a generally cylindrical body member; a rst piston in said body member; means for applying air under pressure to the top of said first piston; a second piston mounted in said body member; means for supplying air to the bottom of said first piston and to the top of said second piston; a sleeve mounted in said body member and operably connected to said second piston for movement therewith, said sleeve having a frusto-conical upper section adapted to engage the tapered wall of a split ring collet to close said collet; means associated with said first piston to raise said sleeve on operation of said first piston; means associated with said second piston adapted to lower said sleeve on operation of said second piston; a ball base xedly mounted between said first and second pistons; said sleeve having an outwardly extending fiange the lower wall of which is tapered upward and outward; said first piston having a downwardly extending flange the inner wall of which is tapered downward and outward; a plurality of balls seated on said ball base and engaging said lower wall of said flange on said sleeve and also engaging downwardly extending fiange on said first piston.

4. A collet comprising: a generally cylindrical body member; a first piston in said body member; means for applying air under pressure to the top of said first piston; a second piston mounted in said body member; means for supplying air to the bottom of said first piston and to the top of said second piston; a sleeve mounted in said body member and operably connected to said second piston for movement therewith, said sleeve having a frusto-conical upper section adapted to engage the tapered wall lof a split ring collet to close said collet; rneans associated with said rst piston to raise said sleeve on operation of said first piston; means associated with said second piston adapted to lower said sleeve on operation of said second piston; the total movement of said first piston being substantially twelve times that of said sleeve; a ball base fixedly mounted between said first and second pistons; said sleeve having an outwardly extending flange the lower wall of which is tapered upward and outward; said first piston having a downwardly extending flange the inner wall of which is tapered downward and outward; a plurality of balls seated on said ball base and engaging said lower Wall of said flange on said sleeve and also engaging downwardly extending flange on said first piston.

'References Cited by the Examiner UNITED STATES PATENTS 787,480 4/05 Tanner 92-62 2,933,070 4/60 Trumper 92-107 3,087,736 4/63 Lukas 279-4 3,143,356 8/64 Pray 279-4 ROBERT C. RIORDON, Primary Examiner. 

1. A COLLET COMPRISING: A GENERALLY CYLINDRICAL BODY MEMBER; A FIRST PISTON IN SAID BODY MEMBER; MEANS FOR APPLYING AIR UNDER PRESSURE TO THE TOP OF SAID FIRST PISTON; A SECOND PISTON MOUNTED IN SAID BODY MEMBER; MEANS FOR SUPPLYING AIR TO THE BOTTOM OF SAID FIRST PISTON AND TO THE TOP OF SAID SECOND PISTON; A SLEEVE MOUNTED IN SAID BODY MEMBER AND OPERABLY CONNECTED TO SAID SECOND PISTON FOR MOVEMENT THEREWITH, SAID SLEEVE HAVING A FRUSTO-CONICAL UPPER SECTION ADAPTED TO ENGAGE THE TAPERED WALL OF A SPLIT RING COLLET TO CLOSE SAID COLLET; MEANS ASSOCIATED WITH SAID FIRST PISTON TO RAISE SAID SLEEVE ON OPERATION OF SAID FIRST PISTON; AND MEANS ASSOCIATED WITH SAID SECOND PISTON ADAPTED TO LOWER SAID SLEEVE ON OPERATION OF SAID SECOND PISTON. 